Safety seat belt retractor

ABSTRACT

A reel-type retractor for a safety belt incorporating an improved automatic locking device. The retractor is designed so that a driving member rotating in accordance with the reel, cooperates with a driven member to actuate a locking device, thus preventing further extension of the belt when the acceleration of the reel exceeds a preselected rate.

United States Patent [191 Beller June 26, 1973 1 1 SAFETY SEAT BELTRETRACTOR [75] Inventor: Herbert 1R. Beller, Mount Clemens,

Mich.

[73] Assignee: Allied Chemical Corporation, New

York, N.Y.

221 Filed: July 13,1971

21 Appl.No.: 162,073

[52] US. Cl. 242/107.4 [51] int. Cl A62b 35/00 [58] Field ofSearch242/107 SB, 107.4,

[56] References Cited UNITED STATES PATENTS 3,632,056 1/1972 Hibbard242/107.4

3,446,454 5/1969 Kovacs et a1. 242/107.4 3,598,336 8/1971 Frost242/107.4 2,845,233 7/1958 Pfannkuch et al 242/1074 PrimaryExaminer-Werner 1-1. Schroeder Attorney-Jonathan Plaut et a].

[57] ABSTRACT A reel-type retractor for a safety belt incorporating animproved automatic locking device. The retractor is designed so that adriving member rotating in accordance with the reel, cooperates with adriven member to actuate a locking device, thus preventing furtherextension of the belt when the acceleration of the reel exceeds apreselected rate.

17 Claims, 5 Drawing Figures PMENTEUJUNES I973 w QE m QE

INVENTOR.

HERBERT R. BELLER A 5LIVT PATENIEDJUNZG W3 SHEET W 2 INVENTOR. H ERB ERTR. BELLER SAFETY SEAT BELT RETRACTOR 1. Field of the Invention Thisinvention relates to safety belt retractors, and more particularly tothose retractors which are normally unlocked when the belt is extendedand buckled about the user but automatically lock in response to theforces which develop during the moment of impact should a collisionoccur.

II. Description of the Prior Art Emergency-locking seat belt retractorsusually have a reel which is connected to the belt for retraction. Inthese retractors of the prior art, the reel is normally unlocked underordinary driving conditions even though the belt is buckled about theuser, thus paying out more belt or taking up the slack in accordancewith the normal movements of the individual. A locking device isprovided, responsive to the forces which develop at the moment ofimpact, thus preventing further extension of the belt and retaining theuser in his or her seat.

The state of the art in this type of retraction device is exemplified byreference to U.S. Pat. Nos. 3,341,250; 3,348,789; 3,412,952; 3,446,454;3,450,368; 3,467,337; and 3,482,799.

Many of these prior art devices are unduly complex, are not fail-safe inconstruction and are not positive acting, incorporating parts which mayfail with wear or in the event that a lubricant should inadvertentlyreach their friction surfaces.

SUMMARY OF THE INVENTION An automatic seat belt retracting device isdisclosed having a locking member which is biased in a locking position,but is normally held in an unlocked position by a cam. This cam isbiased to retain the locking member in its'unlocked position under thoseconditions when the retracting reel is fully retracted or when the beltis extended at a substantially uniform rate or at a low rate ofacceleration. When the reel is turned at a rapidly accelerated rate evenfor a matter of milliseconds, however, such as would occur when the usermoves against the belt under crash conditions, a driven rotating memberacting through the cam actuates the lock bar into locking e'ngagmentwith the reel, thus preventing further extension of the belt. This ispositive, fail-safe action and no friction surfaces are involved at thispoint of criticality. As an added feature to prevent the possibleannoyance of the belt locking while being extended during the bucklingoperation, a slip clutch is included in the retractor connecting thebelt wind-up reel and the locking device. This clutch retains thelocking member in the unlocked position under all circumstances wherethe amount of belt withdrawn drawn is insufficient for buckling and alsoduring periods of continuous extension of the belt as occurs during theprocess of buckling up.

Objects and attendant advantages of the present invention will bereadily appreciated as the same becomes better understood by referenceto the following detailed description when considered in connection withthe accompanying drawings.

DESCRIPTION OF THE DRAWINGS The description refers to the accompanyingdrawings in which like reference characters refer to like partsthroughout the several views:

FIG. I is a perspective view of an automatic locking retractorillustrating the preferred embodiment of the invention showing the beltpartially wound on the reel. A cover or housing for the reel structureincluding an opening to guide the belt onto the reel is not shown.

FIG. 2 is an exploded view of the preferred retractor of FIG. 1. Theseat belt is not included.

FIG. 3 is a cut-away side view in elevation showing in continuous line,the relationship between the cam in the cam plate and the cam follower.In this illustration the cam is retaining the lock bar, which isattached to the cam follower, in its unlocked position. Also shown, inphantom, is the relationship between the cam and the cam follower whenthe locking bar (not shown) is in looking engagement with the reel.

FIG. 4 is a cut-away side view in elevation representing the innersurface of the support wall. Here the relationship is shown between theextended arm of the clutch disc and the cam follower when the lockingbar (not shown) is in unlocked position, and most of the belting (notshown) is on the reel. Also shown, in phantom, is the position of thecam follower while the lock bar is still in the unlocked position, and aconsiderable amount of belt has been withdrawn from the reel.

FIG. 5 is a cut-away side view in elevation of a portion of theretractor drawn from the same viewpoint as that of FIG. 4. Here theextended arm of the clutch plate is shown in sliding contact with thecam follower when the latch bar (not shown) has been urged into lockingengagement with the ratchet due to a sudden increase in the rate ofrotation of the reel. Also shown, in phantom, is the relationshipbetween the cam and extended arm of the clutch when belting is beingwithdrawn from the reel and the roll of belting on the reel is stillsubstantially large.

Referring now the preferred retractor assembly of FIG. 1 andparticularly to the exploded view of FIG. 2; circular toothed gear 25 isfixedly attached to reel shaft 8 at its milled end 43. This gear may bepressed on, it may be keyed to the shaft or it may be an integral partof said shaft. Cam plate 20 is now slipped over the other end of theshaft, said shaft extending through opening 22 so that the cam plate isrotatable in respect to the shaft. To continue with the assembly, end 10of shaft 8 is now inserted into opening 11 of support structure 2 so asto be rotatable. Coiled spring 19 is now placed over the end of shaft 8which is extending into the space between the walls of support 2. Next,clutch plate 18 is slipped over the end of the shaft and is rotatablewith respect to it. Whereas the other elements so far discussed aregenerally fabricated of metal, this clutch plate is preferablyfabricated from a light plastic material, such as nylon. End 10 of shaft8 is now inserted into opening 7 of belt-reel 31 and is extended throughcylindrical portion 6 until it extends through opening 41 on theopposite flange. The shaft is fixed to reel 31. In the particularembodiment shown, a flattened portion of shaft 8 keys the reel to theshaft, since openings 7 and 41 have a shape corresponding to thecross-section of the shaft. Finally, spacer 12, which also may befabricated of a tough plastic material such as nylon, is slipped overthe end of the shaft before said shaft is extended through opening 21 ofsupport structure 2. Openings 11 and 21 are both bearings in which theshaft is journaled. The bifurcated end of shaft now extends into thecenter of spiral ribbon spring 13 so as to firmly secure the flattenedinner end 14 of the spring. The attachment of the spring to spring caseis will be covered later.

The latch bar assembly 29 which engages ratchet faces 55 on theperiphery of the flanges or reel 31 comprises lock bar 51 having a sidemember 52 at each end perpendicular to the bar and facing each other.Preferably, the edges 53 of these end members are also perpendicular tothe surface of lock bar 51. In the embodiment here illustrated, twooutwardly raised projections 33 have been embossed into the sidemembers, said projections serving to space the latch bar between theside walls 4 of support structure 2 when said latch bar is installedbetween them. As shown, cam follower 34 extends outwardly from endmember 52 of the latch bar. Sensing shoe 30 is positioned at point 44 ofthe latch bar and fixed in place by rivets inserted through the shoe andthrough the latch bar at points 45. In continuing with the assembly ofthe retractor, the looped end of spiral spring 39 is slipped over pivotpin 35 which is then inserted into opening 46 in the parallel walls 4 ofsupport 2. The portion of pivot pin 35, which now extends between thetwo support walls 4, is passed through opening 54 of the latch barassembly 29. Care must be taken to see that cam follower 34 extendsthrough opening 49 in the support frame and that it also slips intoirregular cam 38 in cam plate 20, which may be rotated on shaft 43 untilit is in proper alignment. Spiral spring 36 is now tensed, slipped overpivot pin 35, then positioned with crooked end 57 of said springextending into opening 56 in the support bed. The pivot pin is nowextended through opening 54 in the opposite side member of the lock bar,then to the opposite wall of support 2 and through opening 46. Springclip 57 is then fitted under tension into groove 58 of pivot pin 35 toprevent its withdrawal. If spring 36 is under tension and properlyplaced, ratchet plate assembly 29 will now be urged into engagement withratchet faces 55 of the seat belt reel 31. The hooked end of spring 39,the other end of which is fastened to pivot pin 35, is now extendedunder tension and hooked into opening 40 of the cam plate, thus biasingthis member in the unlocked direction. Pinion 26 and rotating member 27are shown as two separate parts for clarity of illustration. However,the shank end of the pinion gear is pressed or keyed into the rotatingmember, or is an integral part thereof, and this assembly as a unit isrotatably slipped over spindle 24, so that pinion gear 26 will meshwith, and be driven by, rotating circular toothed gear 25. Pinion 26,with attached rotating member 27, is now secured in place by spring clip28 which is forced under tension into the groove of spindle 24.

The seat belt can now be attached to the reel, preferably by threadingthe belt into the slot in cylindrical portion 6 of the reel, slipping itaround the shaft 8 and back out the slot, then sewing the belt into apermanent loop. The belt is now wound about the drum by rotating thedrum in the direction permitted by the ratchets when in engagement withthe ratchet bar. When the belt is thus fully retracted, spring 13 is putunder moderate tension and flattened end 59 is firmly secured in slot 50of spring case 15, which may, if desired, be of plastic material. Springcase 15 is now firmly attached to the outer support wall 4 of supportframe 2 by inserting bosses 16 on the spring case through openings 17 inwall 4 of the support. The assembly is complete when clutch plate 18 isrotated until arm 37 touches cam follower 34 and pin 42 is pressedthrough opening 61 in support wall 4. In this position, its forward tipserves as a stop for the clutch plate 18 by contacting point 60 in theextended arm when the clutch plate rotates, as is the case when the beltis being retracted.

An outer case for the unit, although not shown, should be provided andthe slot therein for the passage for the belt should be so placed as toserve as a guide for the belt which, upon retraction, is wound on thereel. To aid in this and reduce wear, if desired, small rollers can beplaced at the top and bottom and/or sides of the opening, which mayrotate with the belt on contact. Opening 58 of FIGS. 1 and 2 is used forattaching the retractor to the vehicle.

In operation, it can be seen that as the belt is first withdrawn fromthe reel, the ratchet assembly 29 cannot, under any circumstance, engagethe ratchet faces because sensing shoe 30 glides over the surface of thelarge roll of belt and prevents the lock bar to which it is attachedfrom reaching the ratchet faces. As the belt is withdrawn to a greaterextent, however, this particular means of keeping the ratchet bar fromthe ratchet faces is no longer effective. When the belt is firstwithdrawn, however, the pressure of clutch plate 18 against flange 5 ofthe reel, said pressure being produced by the effect of spiral spring19, causes the clutch plate to rotate together with the reel flangeuntil stopped by contact with cam follower 34, as shown in FIG. 5 inphantom. The contoured tip of 37 has trapped the cam follower and, aslong as the belt is withdrawn continuously, no engagement between thelock bar and the ratchet faces on the reel is possible. Under thesecircumstances, the reel will not lock even if the rate of accelerationof the reel becomes very rapid, thus, if the user were to yank the beltfrom the retractor, it still would not lock. If now the belt ispermitted to retract even a trifle, the clutch will rotate with the reeland the arm 37 attached thereto will lift away from the cam follower asshown in FIG. 4. If very little belt has been withdrawn, the sensingshoe attached to the lock bar will keep the cam follower insubstantially the position shown in FIG. 4 in solid line. Thus, ifextension of the belt is continued, the arm 37, being a part of theclutch plate, will move down again, trapping the cam follower, as shownin phantom in FIG. 5. If, however, enough belt has been withdrawn toenable a user to buckle up," the sensing shoe will permit the lock barand the cam follower to move because of spring 36 to the position shownin phantom in FIG. 4. If now the belt is extended further, arm 37 willagain rotate downwardly and contact the cam follower 34, as shown insolid line in FIG. 5. It is now clear that the cam follower is no longertrapped by arm 37, but is free to slide beneath it. This action ofitself will not cause the lock bar to engage the ratchet face, but itwill permit the cam to do so should the proper conditions arise. FIGS. 4and 5 present the view which can be had when looking at the extended armof the clutch from a point between the two side walls of the support.FIG. 3, however, presents an exterior view of the cam follower in theirregular cam, as seen from a point outside of the retractor. The camfollower is no longer trapped by the end of the extended arm of theclutch plate, but it is now prevented from moving into a position ofengagement with the ratchet faces by the shoulder in the irregular camsurface, since spring 39 biases the cam plate in this direction. The camfollower is not permitted to engage the lock bar, hence the cam may besaid to be biased in the unlocked position.

When the seat belt is withdrawn from the reel at a uniform rate or evenwhen it is withdrawn at a moderately accelerated rate, the angular forcewhich develops in the cam plate is insufficient to overcome the bias ofspring 39. The user can therefore withdraw the belt and buckle upwithout the annoyance of having the belt locked before fully extended.Once the belt has been buckled in place, the individual can move aboutwith case. If the user moves forward, the belt is extended toaccommodate this motion. If the user sits back in the seat, theretractor takes up the slack. Therefore, at all times the belt applies aslight pressure but is generally unrestricting to normal movements. Theseat belt retractor is now in the position shown in FIG. 1. In FIG. 3,the relationship between the cam and cam follower under these normalcircumstances is illustrated, as well as the position of the cam plate.If the users last motion was toward the back of his seat, therelationship between the extended arm of the clutch and the cam followerwould be as illustrated in FIG. 4 in phantom, whereas if his last motionwere away from the back of his seat, the relationship between theextended arm of the clutch plate and the cam follower would be identicalwith FIG. 4 except that the extended arm 37 of the clutch plate would bedown and in contact with the cam follower in the position shown inphantom. If now the users body lurches forward as he would doinadvertently should the vehicle become involved in a collision, thesudden, momentary extension of the seat belt imparts a momentary highrate of acceleration to both the belt reel and the circular toothed gear25 which is attached thereto. The force applied to pinion gear 26 androtating member 27 imparts a force on the. rotatable cam plate inopposition to biasing spring 39, thus moving the cam plate to theposition shown in phantom, in FIG. 3 and permitting the cam follower andattached lock bar to move into locking engagement with the ratchet facesof the reel, thereby preventing any further extension of the seat beltand restraining the user.

An important feature of the retractor of the present invention is thefact that it can be readily modified to accommodate the different typesof vehicles in which it might be used. For example, when the device isused in airplanes, it should be responsive only to comparatively highrates of acceleration, whereas when used in motor cars, a sensitivity tolower rates of acceleration is appropriate. The greater the tension onspring 39, the greater the rate of acceleration required in order toactivate the locking mechanism. Increasing the ratio between theeffective diameter of the driving gear, or circular toothed gear to theeffective diameter of the driven gear or pinion, decreases thesensitivity to acceleration. Increasing the mass of the rotating member27 also increases the sensitivity of the device to lower rates ofacceleration.

In the embodimentillustrated, weight 23 balances the cam plate and itsattachments about its point of rotation which is the reel shaft 8.Obviously if the mass 27 were increased or decreased to correspondinglyincrease or decrease the sensitivity of response of the mechanism to acertain anticipated rate of acceleration, the counter-balance 23 wouldbe increased or decreased accordingly. The reason for the counterbalanceis to render the device totally non-responsive to rapid deceleration ofthe vehicle. As shown, the deratchet rather than away from it. If thecam plate biasing means should break, or if the clutch spring shouldbreak, the retractor would still lock in an emergency. Even if the latchbar spring were to break, the cam would urge the ratchet bar intoengagement with the ratchet.

Still another feature of the embodiment shown is the fact that the lockbar, when in locking engagement with the ratchet, is perpendicular tothe base and the forces applied against it by the ratchets are alsoperpendicular to the base. Since the bottom edge 53 of the end mem bersof the lock bar are perpendicular to the face of the lock bar, thelocking action is very positive and comparatively little of the force istransmitted to pivot pin DESCRIPTION OF THE PREFERRED EMBODIMENT Thepreferred embodiment of the present invention comprises a supportadapted to be fixedly connected to a vehicle and providedwith a pair ofspaced parallel walls. A spring biased reel is journaled on the wallsand connected to one end of a seat belt so that as the reel is rotatedin one direction, the belt is retracted into a roll and as the belt isunwound from the reel, it rotates in the opposite direction. The reelflanges have ratchet faces on their periphery designed for free motionin the direction of belt retraction, but for locking engagement with apawl in the direction of belt extension. A pawl is mounted on thesupport for motion between a first position in which it is engagablewith the ratchets and a second position in which it is separated fromthe ratchets.

The pawl is biased in the direction in which it is in locking engagementwith the ratchets, but when the belt is fully retracted, or when it isextended at a substantially uniform rate or at a low rate ofacceleration, it is maintained in its second position out of engagementwith the ratchets by a cam member. This can member comprises a platepivotally arranged on the axel of the reel, said axel extending througha journal in one wall of the support, then through a bearing in the camplate. The extended end of the axel terminates in a gear, which is anintegral part of the axel, said gear serving to secure the cam plate inplace at its pivot point. The cam surfaces of this cam plate areirregular, and guide a cam follower which is attached to the pawl, saidcam follower comprising a shaft extending from a portion of the pawlwhich is parallel to the support adjacent to the cam member. This shaftextends in the direction of the support wall, passes through asubstantially unrestricting slot in the support wall and engages the camsurfaces of the cam plate beyond'said wall. The cam surfaces permit twopositions of the pawl, but normally it is retained by biasing meanstothat position which keeps the pawl disengaged with respect to theratchets.

A shaft extends outwardly from the exposed surface of the cam plate, andserves as the spindle for a pinion gear, rotatably positioned thereon,so that said pinion meshes with the gear which terminates the extendedaxel of the reel. A relatively heavy mass such as a disc or wheel iskeyed to, or is an integral part of the pinion, the pinion and bodycomprising an assembly rotatably positioned on the aforementionedspindle. The cam plate is part of a cam plate assembly comprising saidcam plate, the pinion gear and pinion shaft, the rotatable heavy massand the means for retaining the rotatable pinion and attached inertialbody on the pinion shaft. Preferably, it also includes a counter-weightdescribed below. This cam plate assembly is rotatable about its bearingon the extension of the take-up reel axel, being rotatable within limitsimposed by the action of the cam and cam follower. The counter-weight isaffixed to, or is a part of the cam plate assembly, being securelypositioned on the plate to balance the cam plate assembly about theextended take-up reel axel on which it rotates, thus the axel thenextends through the center of gravity of the cam plate assembly andrenders it non-responsive to any force of acceleration or decelerationimparted to it by the action or motion of the vehicle to which theretractor is affixed.

When the belt is normally extended, as when buckled over a passengerslap, the cam plate is held in its unlocked position by the biasingmeans, and as the gear on the reel axel turns, the enmeshed pinion andattached mass revolves in the opposite direction, preferably at agreater angular velocity than that of the driving gear. If, on the otherhand, the belt starts to move at a highly accelerated rate, as wouldhappen if a collision caused the belted passenger to lurch forward, therotatable mass is so slow to respond, that the driving gear acts againstthe pinion in a direction opposite to that applied to the cam plateassembly by the biasing means and with superior force. This force,acting against the pinion which is attached thereto, causes the entirecam plate to rotate about its center of gravity within the allowablelimits, and thus to move against the effect of the biasing means to itsrelease position. The cam follower thereupon permits the biased pawl tomove into locking engagement with the ratchets, thus permitting nofurther extension of the seat belt, and holding the passenger in hisseat.

Also incorporated into the preferred embodiment of the retractor deviceof the present invention is mechanism which prevents the lockingengagement of the pawl with the ratchet under certain circumstances,even when the belt is extended at a high rate of acceleration. Thesecircumstances are those wherein the belt has been extended a selecteddistance, insufficient to permit buckling, and wherein the belt iswithdrawn continuously from the retractor without permitting anappreciable degree of retraction. The purpose of this mechanism is topermit the user to withdraw the belt, even vigorously if so inclined,without causing momentary engagement of the pawl and ratchets. Briefly,this additional mechanism involves the use of a slip clutch connectingthe belt wind-up reel and the locking mechanism.

To accomplish this, one of the two ratchets functions as a drivingclutch plate and is in frictional engagement with a corresponding biaseddriven clutch plate on the axel common to the reel, and disposed betweenthe driving clutch plate and its adjacent wall. A spring between thewall and the driven clutch plate urges it toward the driving clutchplate so that as the reel is rotated, the driven clutch plate can befrictionally rotated through a limited angle of rotation between twopositions.

This driven clutch plate is of a light weight material such as nylon toincrease responsiveness to the action of the driving clutch plate. Anarm extends from the driven clutch plate, of such length that when thebelt is being withdrawn, and the driven clutch plate to which it isattached turns correspondingly within set limits, the arm comes incontact with a portion of the shaft comprising the cam follower.Alternatively, when the belt is retracted, the driven clutch plate,still following the driving clutch plate which is also a ratchet, turnscorrespondingly, and lifts the arm out of contact with the shaft of thecam follower.

The pawl assembly comprises a movable member which as a single unitspans the take-up reel to thus serve as a pawl for both ratchets. It hasat a point between the ratchets, a shoe which slides over the surface ofthe bolt roll as it is extended or retracted. The roll is reduced indiameter as the belt is extended. The biased pawl moves in accordancewith the changing diameter of the roll, with the shoe acting as thesensing element. The motion of the pawl, however, is normally arrestedby the limiting action of the cam, before it is urged all the way intolocking engagement with the ratchets. Its biased motion as the belt isunrolled from the reel, is also arrested by the arm of the driven clutchplate in the following manner:

When the extension of the belt is first begun, and the roll of beltingremaining on the reel has a relatively large diameter, the shoe of thepawl in contact with the roll of belting, keeps the cam followerattached to the pawl at a point in the cam surface of substantiallymaximum distance from the axel of the reel. The motion of the reelcauses the driven clutch plate with attached arm to move in accordancewith the reel until said arm contacts the shaft of the cam follower aspreviously explained. The end of this arm is contoured, with the upperportion extending over the shaft of the cam follower. The lower portionis contoured to substantially fit against the aforesaid shaft so as totrap it as it moves forward as the belt extends, and the shoe or sensingelement of the pawl follows the diminishing radius of the roll. As longas the belt is stationary, or is extended, this arm continues to trapthe cam follower thus restraining the pawl against its biasing means andprevents locking engagement of the pawl with the ratchets. If, whileonly a preselected amount of belt is extended, and the remaining roll ofbelting on the reel has a relatively large diameter, the belt ispermitted to retract any appreciable amount, the clutch will lift anddisengage the arm. 0n continuing with the extension under thesecircumstances, the arm will immediately be moved into position by theclutch to again trap the shaft of the cam follower thus, when only ashort length of belting has been extended, engagement of the pawl withthe ratchets is prevented under all circumstances.

When sufficient belting is unwound to permit a passenger to buckle up,however, the sensing shoe on the biased pawl permits the cam followerattached thereto to move forward within the limits of the cam surfaces.These surfaces still normally prevent the pawl from engaging theratchets, but they permit sufficient movement of the pawl and attachedcam follower toward the latching position so that when the belt isfurther extended, and the clutch activated arm is lowered in contactwith the shaft of the cam follower, said shaft has moved out of reach ofthe contoured end of the arm. The arm merely rests on top of the shaftand can no longer trap it. Thus, if the belt extension is smartlyaccelerated as in a collosion, the cam moves to permit the latch bar toengage the ratchets, and the shaft of the cam follower in contact withthe arm slips beneath it, without being entrapped or impeded.

The sensitivity of the retractor mechanism to the de gree ofacceleration to which it is to be responsive, may

. be adjusted toward increased sensitivity as applicable to slow movingvehicles, by increasing the mass associated with the driven pinion, bydecreasing the tension on the biasing means of the cam plate, and/or byincreasing the ratio of the effective diameter of the driving gear tothe effective diameter of the driven gear. Normally this ratio wouldfall within the range of 1.5:1 to with a ratio of about 2:1 beingespecially preferred for automotive seat belt retractors. Obviously, thesensitivity can be reduced as would beappropriate for airplane seat beltretractors by making one or more, or all of these modifications in theopposite direction.

The retractor of our invention is positive acting since it does notdepend on friction surfaces at the point of criticality. It issubstantially fail-safe in design, simple to manufacture, and easilyadjusted or modified for the desired sensitivity of response.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology which has been used is intended to be inthe nature of words of description rather than of limitation.

Many modifications or variations of the present invention are possiblein the light of the above teachings. It is therefore to be understoodthat within the scope of vthe appended claims, the invention may bepracticed otherwise than as specifically described.

I claim:

1. In a safety seat belt system, the combination comprising:

a. a support having a base and two walls extending therefrom;

b. a sahft journaled on the support;

c. a reel adapted for connection to a seat belt, said reel being fixedconcentrically to the shaft for rotation in a winding direction and inthe opposite, unwind direction;

d. a biasing member connected to the reel urging it to rotate in itswinding direction;

e. a locking member mounted pivotally on the support so as to be movablebetween a locking position in which it is operable to stop rotation ofthe reel in its unwind direction, and a release position in which it isinoperable to stop reel rotation;

f. biasing means urging the locking member into locking engagement withthe reel, said locking member being actuated between the unlockedposition and the locked position by a movable cam;

g. a cam plate including the cam, said cam plate being pivotallypositioned on an extension of the journaled shaft, and movable between afirst position and baised to this position wherein it acts on a camfollower attached to the locking member to restrain it in its unlockedposition, and a second position, against its bias, to release the camfollower and the locking member attached thereto, for locking engagementwith the reel;

. a driving rotating member fixedly positioned at the end of said shaft;

i. A driven rotating member positioned on a spindle fixedly extendingperpendicularly from the surface of the cam plate, said driven rotatingmember being positioned to rotate in accordance with the rotation of thedriving rotating member, whereby in response to the reel being rotatedin the unwind direction with an acceleration exceeding a predeterminedrate, an angular displacement of the cam plate to which the drivenrotating member is attached, is effected; and accordingly, a shift ofthe cam, thus actuating the locking member into locking engagement withthe reel.

2. The combination of claim 1 wherein the driving rotating member is acircular toothed gear, and the driven rotating member is a pinion gearengaged therewith for cooperative rotation.

3. The combination of claim 2 wherein the ratio of the effectivediameter of the driving gear to that of the driven pinion gear lieswithin the range of 1.521 and 10.011.

4. The combination of claim 1 wherein the driven rotating membercomprises a rotatable pinion gear concentrically and contiguously fixedto a mass balanced about the axis of rotation of said pinion gear.

5. The combination of claim 1 wherein the cam plate is pivoted on thereel shaft at' the center of gravity of the cam plate as it isconstituted with all its attachements, thereby making it insensitive toforces of acceleration or deceleration induced by the vehicle to whichit is attached.

6. The combination of claim 1 in which the reel comprises a cylindricaldrum having a length at least as great as the width of the belt to bewound thereon, a C cross section, and having parallel concentric guideflanges, one at each end of the drum, provided with peripheral ratchetfaces.

7. The combination of claim 1 in which the locking member comprises alocking bar positioned to simultaneously engage corresponding ratchetfaces on each flange of the reel, said locking member having attachedthereto a cam follower extending through an unrestricting opening in thesupport wall and engaging the cam of the cam plate.

8. The combination of claim 1 in which a sensing shoe extends from andis attached to the lock bar with the end of the shoe in contact with theseat belt wound on the reel, whereby when the belt is fully retracted,the position of the shoe against the belt wound on the reel keeps thelock bar out of engagement with the reel in opposition to the biasingmeans, but when the belt wound on the reel diminishes with extension ofthe belt, the lock bar is urged toward the reel.

9. The combination of claim 8 wherein the cam comprise two smoothlyconnected slots in the cam plate, allowing motion of the cam follower inaccordance with the movement of the locking bar.

10. The combination of claim 5 in which a weight is added to a point onthe cam plate of sufficient mass to insure that the pivot pointcoincides with the center of mass of the cam plate assembly.

11. The combination. of claim 1' wherein the center of mass of the camplate assembly is positioned beneath the pivot point when the retractoris to be mounted in a vehicle which travels in the direction in whichthe belt extends from the reel.

12. The combination of claim 1 wherein the center of mass of the camplate assembly is positioned above the pivot point when the retractor isto be mounted in a vehicle which normally travels in a directionopposite to that in which the belt extends from the reel.

13. The combination of claim 8 in which a clutch plate is rotatablypositioned on the reel shaft between a support wall and biased intofrictional engagement with the reel flange, said clutch plate having anextending arm and said clutch plate being movable to a first positionand a second position by the unwind rotation of the contiguous reelflange wherein in the first position the extending arm traps andrestrains the latching member when the sensing shoe is in contact withthe belt, a second position when the sensing shoe is not in contact withthe belt wherein the extending arm contacts but does not trap orrestrain the latching member, said clutch plate having a third positionto which it is moved by the wind rotation of the contiguous reel flangewherein the extending arm is out of contact with the latching member.

14. The combination of claim 13 wherein the clutch plate with attachedarm is in frictional contact with the reel, whereby it rotates as thebelt is extended, said rotation being terminated by contact of the armwith the cam follower, and similarly, when the belt is retracted, theclutch rotates with the reel until the arm contacts a pin extending fromthe adjacent support wall.

15. The combination of claim 13 wherein the end of the extended arm ofthe clutch contacts an extension of the cam follower at a point betweenthe body of the lock bar, and the support wall adjacent to the camplate.

16. The combination of claim 15 wherein the end of the extended arm ofthe clutch plate is indented to trap the cam follower when contact ismade while the lock bar is positioned by the sensing shoe in accordancewith a substantially full roll of belting on the reel, said entrapmentbeing maintained while the belt is extended but terminated by anappreciable degree of retraction.

17. In a safety seat belt system, the combination comprising:

a. a support having a base and two walls extending therefrom;

b. a reel adapted for connection to a seat belt, said reel comprising acylindrical drum having a length at least as great as the width of thebelt to be wound thereon, a C" cross section, and parallel concentricguide flanges, one at each end of the drum, provided with peripheralratchet faces, the reel being fixed concentrically on a shaft journaledinto a pair of openings in the support wall for rotation in a windingdirection and in the opposite, unwinding direction;

0. a biasing member connected to the shaft to urge the reel assembly torotate in its winding direction;

d. a locking bar mounted on the support, and movable between a lockingposition in which it simultaneously engages corresponding ratchet faceson the flanges to stop rotation of the reel in its unwind direction, anda release position in which it is inoperable to stop reel rotation;

biasing means urging the locking bar into locking engagement with theratchets, said locking member having attached thereto a cam followerextending through an unrestricting opening in the support wall andengaging a cam, said locking member being actuated between the lockedposition and the unlocked position by said cam;

a sensing shoe attached to the face of the lock bar facing the drum,whereby when the belt is fully retracted, the pressure of the shoeagainst the belt roll keeps the lock bar out of engagement with theratchets in opposition to the biasing means, but when the belt rolldiminishes with the extension of the belt, the lock bar is urged towardthe ratchets;

g. a clutch plate rotatably positioned on the reel shaft between asupport wall and a reel flange, with biasing means urging the clutchplate into frictional engagement with the reel flagne, said clutch platehaving an arm extending for touching engagement with a section of thecam follower, the end of said arm being so contoured as to restrain thelatch bar against engagement with the ratchets if the contact is madewhile the lock bar is positioned by the relationship between its sensingshoe and a substantially full belt roll, but so as not to restrain thelock bar if the contact is made while the lock bar is positioned by therelationship between its sensing shoe and a relatively small belt roll;

h. The end of the extended arm of the clutch plate being indented totrap the cam follower when contact is made while the lock bar ispositioned by the sensing shoe in accordance with a substantially fullroll of belting on the reel, said entrapment being maintained while thebelt is extended, but terminated by an appreciable degree of retraction;

i. a cam plate including the cam, said cam plate being rotatablypositioned on an extension of the journaled shaft so as to be parallelto the support wall, said cam plate being biased toward the unlockedposition;

j. a driving rotating circular toothed gear fixedly positioned at theend of said shaft to thus secure the cam plate rotatably between saidgear and the support wall;

k. a driven pinion rotatably positioned on a spindle fixedly extendingperpendicularly from the surface of the cam plate, said driven pinionhaving an appreciable mass and being positioned for cooperation with thedriving gear, whereby in response to the reel being rotated in an unwinddirection at a constant rate, or at an accelerated rate of less than apredetermined value, the pinion will revolve in relation to the rotationof the driving gear, without causing appreciable displacement of the camplate to which it is affixed, against the biasing means, but when thedegree of acceleration exceeds a predetermined rate as fixed by theamount of bias, the mass of the pinion, and the ratio between theeffective diameters of the driving and driven gear, an angulardisplacement of the cam plate is effected; and accordingly, a shift ofthe cam, thus actuating the locking bar into locking engagement with theratchets.

1' i i i

1. In a safety seat belt system, the combination comprising: a. asupport having a base and two walls extending therefrom; b. a sahftjournaled on the support; c. a reel adapted for connection to a seatbelt, said reel being fixed concentrically to the shaft for rotation ina winding direction and in the opposite, unwind direction; d. a biasingmember connected to the reel urging it to rotate in its windingdirection; e. a locking member mounted pivotally on the support so as tobe movable between a locking position in which it is operable to stoprotation of the reel in its unwind direction, and a release position inwhich it is inoperable to stop reel rotation; f. biasing means urgingthe locking member into locking engagement with the reel, said lockingmember being actuated between the unlocked position and the lockedposition by a movable cam; g. a cam plate including the cam, Said camplate being pivotally positioned on an extension of the journaled shaft,and movable between a first position and baised to this position whereinit acts on a cam follower attached to the locking member to restrain itin its unlocked position, and a second position, against its bias, torelease the cam follower and the locking member attached thereto, forlocking engagement with the reel; h. a driving rotating member fixedlypositioned at the end of said shaft; i. A driven rotating memberpositioned on a spindle fixedly extending perpendicularly from thesurface of the cam plate, said driven rotating member being positionedto rotate in accordance with the rotation of the driving rotatingmember, whereby in response to the reel being rotated in the unwinddirection with an acceleration exceeding a predetermined rate, anangular displacement of the cam plate to which the driven rotatingmember is attached, is effected; and accordingly, a shift of the cam,thus actuating the locking member into locking engagement with the reel.2. The combination of claim 1 wherein the driving rotating member is acircular toothed gear, and the driven rotating member is a pinion gearengaged therewith for cooperative rotation.
 3. The combination of claim2 wherein the ratio of the effective diameter of the driving gear tothat of the driven pinion gear lies within the range of 1.5:1 and10.0:1.
 4. The combination of claim 1 wherein the driven rotating membercomprises a rotatable pinion gear concentrically and contiguously fixedto a mass balanced about the axis of rotation of said pinion gear. 5.The combination of claim 1 wherein the cam plate is pivoted on the reelshaft at the center of gravity of the cam plate as it is constitutedwith all its attachements, thereby making it insensitive to forces ofacceleration or deceleration induced by the vehicle to which it isattached.
 6. The combination of claim 1 in which the reel comprises acylindrical drum having a length at least as great as the width of thebelt to be wound thereon, a ''''C'''' cross section, and having parallelconcentric guide flanges, one at each end of the drum, provided withperipheral ratchet faces.
 7. The combination of claim 1 in which thelocking member comprises a locking bar positioned to simultaneouslyengage corresponding ratchet faces on each flange of the reel, saidlocking member having attached thereto a cam follower extending throughan unrestricting opening in the support wall and engaging the cam of thecam plate.
 8. The combination of claim 1 in which a sensing shoe extendsfrom and is attached to the lock bar with the end of the shoe in contactwith the seat belt wound on the reel, whereby when the belt is fullyretracted, the position of the shoe against the belt wound on the reelkeeps the lock bar out of engagement with the reel in opposition to thebiasing means, but when the belt wound on the reel diminishes withextension of the belt, the lock bar is urged toward the reel.
 9. Thecombination of claim 8 wherein the cam comprise two smoothly connectedslots in the cam plate, allowing motion of the cam follower inaccordance with the movement of the locking bar.
 10. The combination ofclaim 5 in which a weight is added to a point on the cam plate ofsufficient mass to insure that the pivot point coincides with the centerof mass of the cam plate assembly.
 11. The combination of claim 1wherein the center of mass of the cam plate assembly is positionedbeneath the pivot point when the retractor is to be mounted in a vehiclewhich travels in the direction in which the belt extends from the reel.12. The combination of claim 1 wherein the center of mass of the camplate assembly is positioned above the pivot point when the retractor isto be mounted in a vehicle which normally travels in a directionopposite to that in which the belt extends from the reel.
 13. Thecombination of claim 8 in which a clutch plate is rotatably posiTionedon the reel shaft between a support wall and biased into frictionalengagement with the reel flange, said clutch plate having an extendingarm and said clutch plate being movable to a first position and a secondposition by the unwind rotation of the contiguous reel flange wherein inthe first position the extending arm traps and restrains the latchingmember when the sensing shoe is in contact with the belt, a secondposition when the sensing shoe is not in contact with the belt whereinthe extending arm contacts but does not trap or restrain the latchingmember, said clutch plate having a third position to which it is movedby the wind rotation of the contiguous reel flange wherein the extendingarm is out of contact with the latching member.
 14. The combination ofclaim 13 wherein the clutch plate with attached arm is in frictionalcontact with the reel, whereby it rotates as the belt is extended, saidrotation being terminated by contact of the arm with the cam follower,and similarly, when the belt is retracted, the clutch rotates with thereel until the arm contacts a pin extending from the adjacent supportwall.
 15. The combination of claim 13 wherein the end of the extendedarm of the clutch contacts an extension of the cam follower at a pointbetween the body of the lock bar, and the support wall adjacent to thecam plate.
 16. The combination of claim 15 wherein the end of theextended arm of the clutch plate is indented to trap the cam followerwhen contact is made while the lock bar is positioned by the sensingshoe in accordance with a substantially full roll of belting on thereel, said entrapment being maintained while the belt is extended butterminated by an appreciable degree of retraction.
 17. In a safety seatbelt system, the combination comprising: a. a support having a base andtwo walls extending therefrom; b. a reel adapted for connection to aseat belt, said reel comprising a cylindrical drum having a length atleast as great as the width of the belt to be wound thereon, a ''''C''''cross section, and parallel concentric guide flanges, one at each end ofthe drum, provided with peripheral ratchet faces, the reel being fixedconcentrically on a shaft journaled into a pair of openings in thesupport wall for rotation in a winding direction and in the opposite,unwinding direction; c. a biasing member connected to the shaft to urgethe reel assembly to rotate in its winding direction; d. a locking barmounted on the support, and movable between a locking position in whichit simultaneously engages corresponding ratchet faces on the flanges tostop rotation of the reel in its unwind direction, and a releaseposition in which it is inoperable to stop reel rotation; e. biasingmeans urging the locking bar into locking engagement with the ratchets,said locking member having attached thereto a cam follower extendingthrough an unrestricting opening in the support wall and engaging a cam,said locking member being actuated between the locked position and theunlocked position by said cam; f. a sensing shoe attached to the face ofthe lock bar facing the drum, whereby when the belt is fully retracted,the pressure of the shoe against the belt roll keeps the lock bar out ofengagement with the ratchets in opposition to the biasing means, butwhen the belt roll diminishes with the extension of the belt, the lockbar is urged toward the ratchets; g. a clutch plate rotatably positionedon the reel shaft between a support wall and a reel flange, with biasingmeans urging the clutch plate into frictional engagement with the reelflagne, said clutch plate having an arm extending for touchingengagement with a section of the cam follower, the end of said arm beingso contoured as to restrain the latch bar against engagement with theratchets if the contact is made while the lock bar is positioned by therelationship between its sensing shoe and a substantially full beltroll, but so as not to restrain the lock bar if The contact is madewhile the lock bar is positioned by the relationship between its sensingshoe and a relatively small belt roll; h. The end of the extended arm ofthe clutch plate being indented to trap the cam follower when contact ismade while the lock bar is positioned by the sensing shoe in accordancewith a substantially full roll of belting on the reel, said entrapmentbeing maintained while the belt is extended, but terminated by anappreciable degree of retraction; i. a cam plate including the cam, saidcam plate being rotatably positioned on an extension of the journaledshaft so as to be parallel to the support wall, said cam plate beingbiased toward the unlocked position; j. a driving rotating circulartoothed gear fixedly positioned at the end of said shaft to thus securethe cam plate rotatably between said gear and the support wall; k. adriven pinion rotatably positioned on a spindle fixedly extendingperpendicularly from the surface of the cam plate, said driven pinionhaving an appreciable mass and being positioned for cooperation with thedriving gear, whereby in response to the reel being rotated in an unwinddirection at a constant rate, or at an accelerated rate of less than apredetermined value, the pinion will revolve in relation to the rotationof the driving gear, without causing appreciable displacement of the camplate to which it is affixed, against the biasing means, but when thedegree of acceleration exceeds a predetermined rate as fixed by theamount of bias, the mass of the pinion, and the ratio between theeffective diameters of the driving and driven gear, an angulardisplacement of the cam plate is effected; and accordingly, a shift ofthe cam, thus actuating the locking bar into locking engagement with theratchets.